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This study is in keeping with the general pattern of dynamical simulations of a set of rigid three-dimensional bodies submitted to unilateral contact constraints with dry friction. An exact formulation (respecting the contact and friction laws) of the problem of predicting the system accelerations and the contact status, in further evolution is proposed. A numerical treatment of this kind of nonlinear problem is presented. This approach is applied to a simple multi-contact example, and yields results in agreement with those of analytical and numerical type, known for this example. To cite this article: C. Le Saux et al., C. R. Mecanique 331 (2003). 相似文献
74.
The study of the interaction of anticancer drugs with mammalian cells in vitro is important to elucidate the mechanisms of action of the drug on its biological targets. In this context, Raman spectroscopy is a potential candidate for high throughput, non-invasive analysis. To explore this potential, the interaction of cis-diamminedichloroplatinum(II) (cisplatin) with a human lung adenocarcinoma cell line (A549) was investigated using Raman microspectroscopy. The results were correlated with parallel measurements from the MTT cytotoxicity assay, which yielded an IC(50) value of 1.2 ± 0.2 μM. To further confirm the spectral results, Raman spectra were also acquired from DNA extracted from A549 cells exposed to cisplatin and from unexposed controls. Partial least squares (PLS) multivariate regression and PLS Jackknifing were employed to highlight spectral regions which varied in a statistically significant manner with exposure to cisplatin and with the resultant changes in cellular physiology measured by the MTT assay. The results demonstrate the potential of the cellular Raman spectrum to non-invasively elucidate spectral changes that have their origin either in the biochemical interaction of external agents with the cell or its physiological response, allowing the prediction of the cellular response and the identification of the origin of the chemotherapeutic response at a molecular level in the cell. 相似文献
75.
Christophe Raynaud Iker del Rosal Franck Jolibois Laurent Maron Romuald Poteau 《Theoretical chemistry accounts》2010,126(3-4):151-163
A new multicentered effective group potential (EGP) is obtained for η6-benzene. Applications on $[\hbox{Ru}_{4}(\hbox{H})_{4}(\hbox{C}_{6}\hbox{H}_{6})_{4}]^{n+}$ clusters (n = 0 or 2) are in excellent agreement with reference DFT studies in terms of geometries, energies and electronic structures. In particular, the small singlet–triplet energy difference (3.8 kcal mol?1) in [Ru4(H)4(C6H6)4]2+ is very well reproduced. This new EGP is nevertheless not free from the limitations associated to this first generation of molecular pseudopotentials. A cautious analysis of the nature and exact role of this EGP is made, which provides new directions for the elaboration of the next generation of EGPs. In addition, the η5-cyclopentadienyl EGP has been used to perform a constrained dynamical simulation for the reaction of Cp2LaH with H2. The energy conservation during the simulation as well as the activation barrier extracted from the simulation clearly demonstrate the good behavior of this EGP in the context of molecular dynamics. Anharmonic effects on this reaction are underlined, further demonstrating the high accuracy of the potential energy surface obtained with EGPs. From a more general point of view, such EGPs are expected to provide accurate albeit low-cost ligand-field effects in organometallic clusters or nanoparticles and to allow dynamical studies at the surface of such compounds. 相似文献
76.
Martina Baeumler Frank Gütle Vladimir Polyakov Markus Cäsar Michael Dammann Helmer Konstanzer Wilfried Pletschen Wolfgang Bronner Rüdiger Quay Patrick Waltereit Michael Mikulla Oliver Ambacher Franck Bourgeois Reza Behtash Klaus J. Riepe Paul J. van der Wel Jos Klappe Thomas Rödle 《Journal of Electronic Materials》2010,39(6):756-760
77.
Dubois F Meunier S Rabau G Poisson F Guyader G 《The Journal of the Acoustical Society of America》2011,130(5):EL284-EL289
The detection of multicomponent signals for which the components are not equidetectable is precisely investigated as a function of the level difference ΔL(i∕j) between components. The detection thresholds are determined for a seven-tone complex signal with random starting phases masked by white noise. Level differences between the components are examined. A model for non-equidetectable conditions based on the statistical summation model is described. The improvement in detection is calculated from the level difference between components that is related to the thresholds for single components. The model predictions are in accordance with the experimental results. 相似文献
78.
Martineau C Engelke F Taulelle F 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(2):311-319
The effects of multiple-resonance heteronuclear decoupling under magic angle spinning (MAS) on the resolution of one-dimensional 19F and 31P and various two-dimensional MAS NMR spectra and on the residual non-refocusable coherence lifetimes in fluorinated aluminophosphate AlPO4-CJ2, i.e. a compound that contains numerous highly abundant nuclei but no homonuclear spin bath, has been investigated. The design of the four-channel (1H, 19F, 27Al, 31P) MAS probe used for this study is first described. 1H and 1H–27Al double-resonance decouplings allows lengthening the optimized transverse relaxation and increasing the resolution in the 19F and 31P dimensions. Under the application of multi-nuclear decoupling, a two-dimensional 19F–31P CP-HETCOR correlation spectrum for AlPO4-CJ2 is recorded with unprecedented high-resolution in the two dimensions. Moreover, because 1H-decoupling increases the 19F , it has been applied during the entire duration of the 2D NMR experiments, allowing the direct use of residual small interactions to generate 19F–19F and 19F–27Al 2D NMR correlation spectra in AlPO4-CJ2. 相似文献
79.
80.
In this paper we consider the motion of a rigid body in a viscous incompressible fluid when some Navier slip conditions are prescribed on the body's boundary. The whole system “viscous incompressible fluid + rigid body” is assumed to occupy the full space R3. We start by proving the existence of global weak solutions to the Cauchy problem. Then, we exhibit several properties of these solutions. First, we show that the added-mass effect can be computed which yields better-than-expected regularity (in time) of the solid velocity-field. More precisely we prove that the solid translation and rotation velocities are in the Sobolev space H1. Second, we show that the case with the body fixed can be thought as the limit of infinite inertia of this system, that is when the solid density is multiplied by a factor converging to +∞. Finally we prove the convergence in the energy space of weak solutions “à la Leray” to smooth solutions of the system “inviscid incompressible fluid + rigid body” as the viscosity goes to zero, till the lifetime T of the smooth solution of the inviscid system. Moreover we show that the rate of convergence is optimal with respect to the viscosity and that the solid translation and rotation velocities converge in H1(0,T). 相似文献